tracing: Check that number of vals matches number of synth event fields

Commit 7276531('tracing: Consolidate trace() functions')
inadvertently dropped the synth_event_trace() and
synth_event_trace_array() checks that verify the number of values
passed in matches the number of fields in the synthetic event being
traced, so add them back.

Link: http://lkml.kernel.org/r/32819cac708714693669e0dfe10fe9d935e94a16.1581720155.git.zanussi@kernel.org

Signed-off-by: Tom Zanussi <zanussi@kernel.org>
Signed-off-by: Steven Rostedt (VMware) <rostedt@goodmis.org>

kernel/trace/trace_events_hist.c

@@ -1878,6 +1878,11 @@ int synth_event_trace(struct trace_event_file *file, unsigned int n_vals, ...)
 		return ret;
 	}
 
+	if (n_vals != state.event->n_fields) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	va_start(args, n_vals);
 	for (i = 0, n_u64 = 0; i < state.event->n_fields; i++) {
 		u64 val;
@@ -1914,7 +1919,7 @@ int synth_event_trace(struct trace_event_file *file, unsigned int n_vals, ...)
 		}
 	}
 	va_end(args);
-
+out:
 	__synth_event_trace_end(&state);
 
 	return ret;
@@ -1953,6 +1958,11 @@ int synth_event_trace_array(struct trace_event_file *file, u64 *vals,
 		return ret;
 	}
 
+	if (n_vals != state.event->n_fields) {
+		ret = -EINVAL;
+		goto out;
+	}
+
 	for (i = 0, n_u64 = 0; i < state.event->n_fields; i++) {
 		if (state.event->fields[i]->is_string) {
 			char *str_val = (char *)(long)vals[i];
@@ -1984,7 +1994,7 @@ int synth_event_trace_array(struct trace_event_file *file, u64 *vals,
 			n_u64++;
 		}
 	}
-
+out:
 	__synth_event_trace_end(&state);
 
 	return ret;